It is well known that organic acids are useful in stimulating the growth of plants. It has been theorized that much of the action of organic fertilizers, such as manure, is due to the presence of organic acids. These organic acids include those such as acids of the citric acid cycle or amino acids.
GABA (.gamma.-aminobutyric acid), 4-aminobutyric acid, is an ubiquitous non-protein amino acid that is found in plants, bacteria and animals. Although the presence of GABA was discovered in plants more than forty years ago, its function remains unknown. As has been pointed out by Satya, Naryan and Nair (Review Article No. 51, Phytochemistry 29:367-375, 1990), the only known function of GABA is as an inhibitory neurotransmitter in animal nervous systems. Commenting on the possible functions of GABA in plants, Chung, et al., (Plant Physiology 99:659-664, 1992) have concluded that "such an abundant and ubiquitous compound will fulfill a significant physiological role". Thus, although an important role for GABA has been suggested, the nature of this role has remained a mystery.